Prior Art
It has already been known to blow prereduced and at least partially preheated charges into a fluidized layer along with coal, wherein coal is gasified in a fluidized layer under reduction of the charge and pig iron as well as slag are drawn off in the liquid states. These known melting gasifying reactions, as a rule, have been optimized in view of the pig iron output sought. In order to be able to produce cement clinker in addition to pig iron, ore together with a batch of lime have already been charged into the melter gasifier according to an earlier suggestion, the desired cement clinker composition having been adjustable by means of the lime batch. By appropriate adjustment of the basicity of the slag, a suitable starting material having hydraulic properties may be synthetized from a series of slags, which starting material may be used either directly as what is called slag cement or as an additive in cement adjustment or in the production of cement. However, strongly basic slags, such as, for instance LD slags, on grounds of their high iron oxide contents, as a rule, are not suitable directly for further utilization in the production of cement. Taking into account the increasing burden of such steel slags and, in particular, LD slags, by heavy metals, the disposal of such slags also constitutes an ever increasing problem. Above all, the relatively high amounts of steelworks slags incurred to date no longer can be utilized in an economic manner, and taking into account the increasing content of heavy metals it is to be feared that also dumping will be encumbered with ever increasing problems.
Binder additives influencing the setting time, the fatigue strength and other parameters essential to binders, have gained more and more importance in the production of hydraulic binders. Such additives may be used in connection with conventional hydraulic binders, such as, for instance, slag cements or portland cements, to adjust the desired properties.